Vybrid GPIO

I'm using a Vybrid MVF61NN151CMK50 processor (Emcraft SOM) and having some weird issues with the GPIO pins. I'm trying to drive some LEDs. The cathode of the LED goes to the 3.3V supply. The anode goes to a resistor (270 ohm) and from there to an IO pin. All of the GPIO clocks are on, the IOMUX registers for these pins are set to 0x00002502 (OBE enabled, open drain enabled, 37 ohm drive, med speed, alt func = 0. The problem is that the LEDs are always on. It doesn't matter whether the PDOR shows the pin high or low. It's like the pulldown transistor won't turn off.

I have a similar situation just trying to drive a GPIO pin high. In this case the IOMUX register is set to 0x00000102 (OBE enabled, 37 ohm drive). The pin is always low, regardless of the value in the PDOR register. What am I missing?